This invention relates generally to latches, and more particularly a fail-safe mechanism allowing a normally open door to be locked when a solenoid is energized. It also relates to a fail-secure mechanism operable to unlock a normally locked door when a solenoid is energized, and vice versa.
Devices heretofore available for the purpose or purposes described herein embody inherently undesirable features, which not only present potential sources of trouble, but also make them more difficult to install and maintain in good operating condition. One problem with such devices concerned the need for relatively large-sized or heavy-duty solenoids capable of exerting sufficient force to unlatch a door. There is need for a small size, compact, fail-safe mechanism wherein the operating solenoid need only produce a very small force to effect fail-safe latching of a normally open door, or to effect failure-secure unlatching of a normally locked door.